Backtalk Doublespeak on Encryption
Storefront-Backtalk magazine had an interesting post on Too Much Encrypt = Cyberthief Gift. And when I say ‘interesting’, I mean the topics are interesting, but the author (Walter Conway) seems to have gotten most of the facts wrong in an attempt to hype the story. The basic scenario the author describes is correct: when you encrypt a very small range of numbers/values, it is possible to pre-compute (encrypt) all of those values, then match them against the encrypted values you see in the wild. The data may be encrypted, but you know the contents because the encrypted values match. The point the author is making is that if you encrypt the expiration date of a credit card, an attacker can easily guess the value.
